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🖋️ Free and open source C++ spell checking library
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About Nuspell

Nuspell is a spell checker library and command-line program designed for languages with rich morphology and complex word compounding. Nuspell is a pure C++ reimplementation of Hunspell.

Main features of Nuspell spell checker and morphological analyzer:

  • Full unicode support
  • Max. 65535 affix classes and twofold affix stripping (for agglutinative languages, like Azeri, Basque, Estonian, Finnish, Hungarian, Turkish, etc.)
  • Support complex compounds (for example, Hungarian and German)
  • Support language specific features (for example, special casing of Azeri and Turkish dotted i, or German sharp s)
  • Handle conditional affixes, circumfixes, fogemorphemes, forbidden words, pseudoroots and homonyms.
  • Free software. Licenced under GNU LGPL.

Building Nuspell


Build-only dependencies:

g++ make cmake git ronn

Runtime dependencies:

boost-locale icu4c

Recommended tools for developers:

qtcreator ninja clang-format gdb vim doxygen

Building on GNU/Linux and Unixes

We first need to download the dependencies. Some may already be preinstalled.

For Ubuntu and Debian:

sudo apt install g++ make cmake libboost-locale-dev libicu-dev

Then run the following commands:

mkdir build
cd build
cmake ..
sudo make install

For speeding up the build process, run make -j, or use Ninja instead of Make.

Building on OSX and macOS

  1. Install Apple's Command-line tools
  2. Install Homebrew package manager
  3. Install dependencies
brew install cmake icu4c boost
export ICU_ROOT=$(brew --prefix icu4c)

Then run the standard cmake and make. See above. The ICU_ROOT variable is needed because icu4c is keg-only package in Homebrew and CMake can not find it by default. Alternatively, you can use -DICU_ROOT=... on the cmake command line.

If you want to build with GCC instead of Clang, you need to pull GCC with Homebrew and rebuild all the dependencies with it. See Homewbrew manuals.

Building on Windows

1. Compiling with Mingw64 and MSYS2

Download MSYS2, update everything and install the following packages:

pacman -S base-devel mingw-w64-x86_64-toolchain mingw-w64-x86_64-boost \

Then from inside the nuspell folder run:

mkdir build
cd build
cmake .. -G "Unix Makefiles"
make install

2. Building in Cygwin environment

Download the above mentioned dependencies with Cygwin package manager. Then compile the same way as on Linux. Cygwin builds depend on Cygwin1.dll.

Building on FreeBSD (experimental)

Install the following required packages

pkg cmake icu boost-libs

Then run the standard cmake and make as on Linux. See above.

Debugging Nuspell

First, always install the debugger:

sudo apt install gdb

It is recomended to install a debug build of the standard library:

sudo apt install libstdc++6-8-dbg

For debugging we need to create a debug build and then we need to start gdb.

mkdir debug
cd debug
cmake .. -DCMAKE_BUILD_TYPE=Debug
make -j
gdb src/nuspell/nuspell

If you like to develop and debug with an IDE, see documentation at


Testing Nuspell (see tests in tests/ subdirectory):

make test

or with Valgrind debugger:

make test
VALGRIND=[Valgrind_tool] make test

For example:

make test
VALGRIND=memcheck make test


Using the command-line tool

The main executable is located in src/nuspell.

After compiling and installing you can run the Nuspell spell checker with a Nuspell, Hunspell or Myspell dictionary:

nuspell -d en_US text.txt

For more details see the man-page.

Using the Library

Including in your program:

#include <nuspell/dictionary.hxx>

Linking with Nuspell static library:

g++ example.cxx -lnuspell -licuuc -licudata
# or better, use pkg-config
g++ example.cxx $(pkg-config --cflags --libs nuspell)

See also

Full documentation in the wiki, which also holds the Code of Conduct.

API Documentation for developers can be generated from the source files by running:


The result can be viewed by opening doxygen/html/index.html in a web browser.


Myspell, Hunspell and Nuspell dictionaries:

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